<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
<form action="/xxx" method="post">
  <input type="text" name="name" id="">
  <input type="text" name="age" id="">
  <input type="text" name="sex" id="">
  <input type="submit">
</form>
</body>
<script>
  let oBtn=document.querySelector(`#btn`)

  // oBtn.onclick=function(){




  // }


</script>
</html>